1. Field of the Present Invention
The invention relates to powered wrenches, and more specifically to power tongs to make-up and/or break-out threaded connections between adjacent tubular segments. In particular, the present invention is directed to an apparatus and method to modify a power tong to grip and rotate tubular segments having an expanded range of diameters.
2. Background of the Present Invention
Oil field tubular segments, e.g. drill pipe, production tubing and casing (hereafter referred to as “tubulars”) are produced in segments that may be coupled (“made-up”) using threaded connections at their ends to form tubular strings. Power tongs are used to make-up and/or to uncouple (“break-out”) threaded tubular connections by gripping a first tubular with a back-up tong, and by gripping and rotating an adjacent, second tubular relative to the first tubular. Power tongs are typically hydraulically-powered devices, but may be, for example, pneumatically, electrically and/or mechanically driven.
FIG. 1A is a perspective view of one embodiment of a prior art power tong 100 that can be modified using a method and/or an apparatus of the invention. The embodiment of the power tong 100 in FIG. 1A may comprise a lifting member 20 to secure the power tong to a crane or hoist, a hydraulically-powered drive motor 15, and a gripping assembly 104 coupled to the drive motor 15 to grip and rotate a tubular (not shown in FIG. 1A).
The gripping assembly shown in FIG. 1A comprises a generally “C”-shaped gear housing 12 pivotally supporting a pair of hinged doors 14A, 14B to secure the bay, or opened (indicated by arrows 14A′ and 14B′) about hinges 18 using handles 16 to introduce a tubular into the bay 19.
The center of the bay 19 in FIG. 1A is generally intermediate a pair of opposed, pivotable gripping jaws 20, 21 (gripping jaw 21 not shown). Each gripping jaw may pivot between a retracted position and a gripping position about a pin or bolt 22. When cammed to the gripping position, the arcuate gripping faces 20C, 21C (gripping face 21C not shown in FIG. 1A) are displaced one toward the other to grip a tubular that may be introduced into the bay 19.
FIG. 1B is a perspective view of one embodiment of a prior art rotary gear 40 that can be rotatably disposed within the gear housing (element 12 of FIG. 1A) to cam the gripping jaws 20, 21 to grip a tubular received in the bay (see FIG. 1A). The rotary gear 40 is a generally “C”-shaped gear having slot 46A rotatably alignable with the throat 46 of the gear housing to receive a tubular into the bay 19. The rotary gear 40 in FIG. 1B further comprises a row of gear teeth 41 along its periphery to be driven by pinion gears, and an interior cam surface 44 to cam the gripping jaws from the retracted position to a gripping position. A “tooth,” as that term is used herein (as singular form of “teeth”), is a engagement unit on or near the periphery of a rotary member, such as a gear, sprocket, or disc, that provides a generally non-slip means of engaging and rotating an adjacent rotary member.
The rotary gear of FIG. 1B may be rotatably secured within the gear housing 12 to surround the gripping jaws 20, 21 with the cam surface 44. The power tong 100 includes a rotary gear drive motor 15 (see FIG. 1A) to drive the plurality of pinion gears driving the teeth 41 and thereby transfer torque from the drive motor 15 to the rotary gear 40 (see FIG. 1B).
FIG. 2A is a cross-section plan view of the retracted gripping jaws 20, 21 of FIG. 1A surrounded by the cam surface 44 of the rotary gear of FIG. 1B after a tubular 90 is positioned within the bay 19 and between the gripping jaws 20, 21. The cross-section plane of FIG. 2A is through the gripping jaws 20, 21 and intermediate an upper cage plate and a lower cage plate described below in relation to FIG. 3. Gripping jaws 20, 21 are pivotable from their retracted position (see FIG. 2A) by powered rotation of cam surface 44 and rotary gear 40. Gripping jaws 20, 21 may be fitted with dies 30 to grip the tubular 90.
FIG. 2B is the cross-section plan view of FIG. 2A after clockwise rotation of rotary gear 40 through an angle to cam the cam rollers 20D, 21D from recesses 42 in the cam surface 44 of the rotary gear 40, and to thereby pivot the gripping jaws 20, 21 to grip the exterior of the tubular 90. Continued rotation of the rotary gear 40 within gear housing (see FIG. 1A) beyond the position shown in FIG. 2B cams gripping jaws 20, 21 into tighter engagement with the tubular 90 and rotates gripping jaws 20, 21, the cage plates that are coupled to the gripping jaws (described below in relation with FIG. 3) and the gripped tubular 90. Rotation of the rotary gear 40, the gripping jaws 20, 21 and the tubular 90 may continue until the threaded connection between the tubular 90 and the adjacent tubular (not shown in FIG. 2B) is broken out.
Breaking out a right-handed threaded connection using the power tong depicted in FIGS. 1A-2B requires counterclockwise rotation of the rotary gear 40 within the gear housing 12 to initially actuate the gripping jaws 20, 21 to engage the tubular 90. Continued counterclockwise rotation of the rotary gear 40 rotates tubular 90 to break-out a threaded connection between the tubular 90 and the adjacent tubular below the tubular 90 shown in FIGS. 2A and 2B.
It should be understood by those skilled in the art that the sequence of FIGS. 2A and 2B illustrate the gripping of a tubular 90 to break-out a right-handed connection or to make-up a left-handed threaded connection, and that FIG. 2B would be transposed to illustrate the movement of gripping jaws to make-up a right-handed threaded connection or to break-out a left-handed threaded connection.
FIG. 3 is an exploded perspective view of one embodiment of a prior art cage assembly that may be used in the power tong of FIG. 1A. The cage assembly 106 of FIG. 3 comprises a generally “C”-shaped upper cage plate 30 having a plurality of apertures to receive pins 22 or bolts 2 to secure upper cage plate 30 in a spaced-apart relationship to a generally “C”-shaped lower cage plate 10. The lower cage plate 10 and the upper cage plate 30 in FIG. 3, and the pins 22 and bolts 2, form a cage assembly pivotally securing gripping jaws 20, 21 within the cage assembly 106 with bolts 22. Gripping jaws 20, 21 in FIG. 3 each comprise a gripping face 20C, 21C to grip a portion of the exterior of a tubular introduced between the gripping jaws 20, 21. The gripping jaws 20, 21 in FIG. 3 each comprises a pin bore 20E, 21E to receive a pin 22, a pivot end 20A, 21A, a distal end 20B, 21B, and a cam follower 20D, 21D. Gripping jaws 20, 21 in FIG. 3 are shown in the retracted position within the cage assembly 106 to accept a tubular, and may be cammed by cam surface 44 of the rotary gear 40 (see FIGS. 2A and 2B) to pivot about pins 22 and displace gripping faces 20C, 21C to grip a tubular.
Cage assembly 106 may be positioned within and rotatable with the rotary gear 40 (see FIG. 1B) rotatable within gear housing 12 (see FIG. 1A). Each gripping jaw 20, 21 shown may comprise a cam roller or cam lobe 20D, 21D to rollably and/or slidably follow cam surface 44 of rotary gear 40 (see FIGS. 2A and 2B). Gripping faces 20C, 21C (gripping face 21C not shown in FIG. 3) of gripping jaws 20, 21 may be arcuate to correspond to the exterior of the tubular to be gripped. Optionally, dies 30, like those shown in FIGS. 2A and 2B, may be releasably disposed on gripping faces 20C, 21C to grip the external surface of a tubular 90 in the bay 19.
FIG. 4 is a perspective view of the assembled prior art cage assembly 106 of FIG. 3 vertically aligned with bay 19 of the gripping assembly 104 and positioned to be installed in the bay. Gripping assembly 104 in FIG. 4 provides a peripheral shoulder 5 generally surrounding the bay 19 and interrupted at the throat 46 of gear housing 12, and the shoulder 5 corresponds to a protruding lip 7 of cage assembly 106. FIG. 4 reveals cam surface 44 of the rotary gear 40 rotatably disposed within gear housing 12 and rotatable by operation of the drive motor 15.
FIG. 5 is a perspective view of the cage assembly 106 of FIG. 4 after installation within the bay 19 of the gripping assembly 104. Gripping jaws 20, 21 (gripping jaw 20 not shown) are in the retracted position to receive a tubular there between. Gripping jaws 20, 21 may be cammed by rotation of the rotary gear 40 to pivot gripping jaws 120, 21, one toward the other, to engage a tubular that may be received within the bay 19.
FIG. 6A is a plan view of the gripping assembly 104, and portions of the cage assembly 106 shown in FIG. 5, after a tubular 90 (shown in cross-section) is introduced through the throat 46 and into the bay 19 of the gripping assembly 104, and after the rotary gear 40 is rotated counterclockwise through a first angle to cam the gripping jaws 20, 21 to grip the tubular 90. Rotation of the rotary gear closes at least some of the throat 46. A portion of the peripherally protruding lip 7 of upper cage plate 30 (shown in FIGS. 4 and 5) is omitted from FIGS. 6A-6C to reveal the interaction between the cam followers 20D, 21D of the gripping jaws 20, 21 and the cam surface 44 of the rotary gear 40.
FIG. 6B is the top plan view of FIG. 6A after the rotary gear 40 is further rotated counterclockwise from the position shown in FIG. 6A to rotate the cage assembly 106 and the tubular 90 gripped by the gripping jaws 20, 21.
FIG. 6C is the plan view of FIGS. 6A and 6B after further counterclockwise rotation of the rotary gear 40 from the position shown in FIG. 6B to rotate the tubular 90. The rotary gear 40 maintains the angular position relative to the cage assembly 106 and tubular 90 in FIG. 6B. Rotation of the tubular 90 can continue until the threaded connection is made-up and the desired torque is applied to the connection between the tubular 90 and an adjacent tubular.
FIG. 7A is a plan view of a gripping assembly 104 of one embodiment of a prior art power tong comprising a rotary gear 40 rotatable within a gear housing 12. The rotary gear 40 in FIG. 7A comprises an interior cam surface 44 and a pair of generally opposed recesses 42, each to rollably or slidably receive and surrender a cam follower on a gripping jaw (not shown). Each recess 42 may positioned within the cam surface 44 to receive the follower 20D, 21D (see FIG. 2A-2B) when the slot in the rotary gear 40 is generally aligned with the throat 46 of the gear housing 12.
It should be understood that a prior art power tong may comprise a generally continuous rotary gear. For example, a prior art power tong may comprise a rotary gear that does not comprise a slot to facilitate the introduction of a tubular into the interior bay within the rotary gear. In these power tongs, the tubular to be gripped and rotated by the power tong can be introduced from above or below the power tong by longitudinal movement along its axis relative to the position of the power tong.
In one embodiment, a prior art power tong may have a continuous rotary gear. Additionally or alternatively, a prior art tong can include a continuous upper cage plate and a continuous lower cage plate in a spaced-apart relationship to the upper cage plate, and a plurality of gripping jaws movably secured intermediate the upper cage plate and the lower cage plate. It should be understood that the methods and apparatus described below and claimed herein may be used to make-up and/or break-out tubular connections, or may be used to modify a prior art power tong, of the type having a continuous rotary gear, upper cage plate and/or lower cage plate without departure from the spirit of the invention.
FIGS. 1A-7A are provided and described above to explain the structure and operation of a prior art power tong, and to provide a foundation to better support the disclosure of the invention, which is described below in relation to FIGS. 7B-11.
The shortcoming of the prior art power tong described above in relation to FIGS. 1A-7A is the limited range of diameters of tubulars that may be gripped and rotated to make-up and/or break-out threaded tubular connections. The gripping jaws 20, 21 of a conventional power tong like that described above may be movably secured, for example, pivoted, to grip only a limited range of tubulars, and the range may be limited by, for example, the radial length of grooves into which the gripping jaws are movably keyed, or, for a second example, the distance between the pins 22 that pivotally secure gripping jaws 20, 21 within the cage assembly 106, among other dimensions.
What is needed is a method and an apparatus that may be used to modify a conventional power tong so that it can be used to make-up and/or break-out an increased range of tubular diameters. What is needed is a method and an apparatus that can be used to make a conventional power tong adjustable to use on smaller diameters of tubulars. What is needed is a method and an apparatus to convert a conventional power tong to make-up or break-out threaded connections on tubulars having a diameters smaller than the smallest diameter that the conventional power tong can make-up or break-out without the use of the method and/or the apparatus.